Technical Field
The technical field relates generally to isolation contactor control in an electrical power distribution system for a vehicle and, more particularly, to preventing unscheduled, transitory interruptions in isolation contactor states.
Description of the Technical Field
Electric and hybrid electric vehicles are usually equipped with one or more high voltage, direct current, electrical power distribution subsystems by which power is supplied to vehicle traction motors and other high voltage loads. High voltage isolation contactors have been used to control the energization and de-energization of the high voltage DC power distribution sub-systems and to control the flow of power to loads such as traction motors and vehicle accessory motors. It has been long recognized that the action of opening a high voltage isolation contactor can substantially reduce the service life of the contactor due to arcing. The problem with arcing becomes more pronounced as facing surfaces of a contactor incur surface damage accelerating the process and potentially resulting in premature failure.
The occurrence of unintended transitions of high voltage isolation contactors at times outside the design considerations of the system can be particularly damaging. Such events can also result in system behavior outside of operational modes consistent with reliable operation of electric and hybrid electric vehicles. Among the causes of unintended high voltage isolation contactor transitions which occur when a vehicle electrical power distribution system is energized are: interference in data communication between network nodes of a vehicle control network; compromised energy interfaces; localized drift in the potential level of vehicle ground plains caused by isolated active high voltage electrical potential leaking into the vehicle mass; and compromised or damaged wiring.